If I image with an L-enhance filter do I also need to get full rub data?

[Jay6879]

Do I essentially have to capture the data twice and then combine it in post? Or is imaging just straight L-enhance good enough?

[vlaiv]

No, but you can if you wish.

L-enhence filter is UHC type filter and is suitable for imaging emission type targets - which means Ha regions, Planetary and emission type nebulae and super nova remnants.

These targets emit most of their light in few narrow emission bands - Ha, Hb, OIII, SII, NII and so on.

UHC type filter will pass most if not all of these and cut most of the rest of wavelengths. This means that color of these targets will be good regardless of filter used. What won't be good is star color. You can't get good star color using such filters because stars emit light over whole spectrum and this is very restrictive filter.

You have a choice - you can put up with very strange star colors in your images or you can shoot RGB data for use with stars only. This requires special processing, but good news is that you don't need as much data to capture star colors as you need for nebulosity. This means that you can dedicate just a small amount of time to capture unfiltered star color data and dedicate most of your time to capture target with filter.

If you want to attempt to blend in proper star color, here is workflow that I would recommend:

- shoot target with filter and then create starless version of the image - process it separately

- use starless version of the image to get stars only version of the image

- use unfiltered RGB data to color the stars only version of the image (color transfer)

- blend in two versions in the end - starless processed separately and stars only with true star color transferred.

Btw, don't use this filter on star clusters, galaxies or reflection nebulae - these are all broad band type targets.

[R26 oldtimer]

I assume that you have an osc camera. If that's the case then the image you get is effectively an HOO* narrowband image.  That means that through that filter your camera records Ha emmision on the red channel/pixels and OIII on the blue and green. 

If you split the channels,  you get an Ha image from the red channel and an OIII from the green and blue. You can also stack the green and blue, to increase the OIII Snr.

*actually the l-enhance also allows Hb wavelength along with OIII so the out of the camera image is more of an Ha,OIII+Hb,OIII+Hb

[Jay6879]

4 hours ago, vlaiv said:

No, but you can if you wish.

L-enhence filter is UHC type filter and is suitable for imaging emission type targets - which means Ha regions, Planetary and emission type nebulae and super nova remnants.

These targets emit most of their light in few narrow emission bands - Ha, Hb, OIII, SII, NII and so on.

UHC type filter will pass most if not all of these and cut most of the rest of wavelengths. This means that color of these targets will be good regardless of filter used. What won't be good is star color. You can't get good star color using such filters because stars emit light over whole spectrum and this is very restrictive filter.

You have a choice - you can put up with very strange star colors in your images or you can shoot RGB data for use with stars only. This requires special processing, but good news is that you don't need as much data to capture star colors as you need for nebulosity. This means that you can dedicate just a small amount of time to capture unfiltered star color data and dedicate most of your time to capture target with filter.

If you want to attempt to blend in proper star color, here is workflow that I would recommend:

- shoot target with filter and then create starless version of the image - process it separately

- use starless version of the image to get stars only version of the image

- use unfiltered RGB data to color the stars only version of the image (color transfer)

- blend in two versions in the end - starless processed separately and stars only with true star color transferred.

Btw, don't use this filter on star clusters, galaxies or reflection nebulae - these are all broad band type targets.

 

3 hours ago, R26 oldtimer said:

I assume that you have an osc camera. If that's the case then the image you get is effectively an HOO* narrowband image.  That means that through that filter your camera records Ha emmision on the red channel/pixels and OIII on the blue and green. 

If you split the channels,  you get an Ha image from the red channel and an OIII from the green and blue. You can also stack the green and blue, to increase the OIII Snr.

*actually the l-enhance also allows Hb wavelength along with OIII so the out of the camera image is more of an Ha,OIII+Hb,OIII+Hb

 

This is good! I'm new so I'm not exactly looking to add any more complexity at this point, but I like that the option is there to add it as separate data. One thing I forgot to mention is I have an unmodified Canon T3i, would this filter still make a difference over no filter? 

[vlaiv]

Just now, Jay6879 said:

 

 

This is good! I'm new so I'm not exactly looking to add any more complexity at this point, but I like that the option is there to add it as separate data. One thing I forgot to mention is I have an unmodified Canon T3i, would this filter still make a difference over no filter? 

Yes it will, especially if you live in high light pollution.

It's best to use super pixel mode to debayer your data when you use such filter.

[Jay6879]

25 minutes ago, vlaiv said:

Yes it will, especially if you live in high light pollution.

It's best to use super pixel mode to debayer your data when you use such filter.

I'm jn a bortle 5 location so there is light pollution but not extreme, but I guess if the filter helps cut out even that little but it's only going to improve the image eh? So I should still see a boost in Ha despite my camera being unmodified right?

I've been told a few times already my camera will be useless for nebula so I'm trying to make this work without modifying it!

[vlaiv]

2 minutes ago, Jay6879 said:

I'm jn a bortle 5 location so there is light pollution but not extreme, but I guess if the filter helps cut out even that little but it's only going to improve the image eh? So I should still see a boost in Ha despite my camera being unmodified right?

I've been told a few times already my camera will be useless for nebula so I'm trying to make this work without modifying it!

Ok, so what you need to understand is - there is no On/Off approach here.

Saying that your camera is useless for Ha is simply not true. It can only be useless if it has 0 sensitivity in Ha line and that is not true.

What is true is that your camera might need x5 total exposure versus other Ha modded camera to achieve same signal to noise ratio.

Similar reasoning goes for use of filter if it is properly used. It will shorten the time needed to reach certain signal to noise ratio. Only difference being - which part of Signal to Noise Ratio (SNR) it operates on.  Modified camera improves signal detection - so it operates to increase signal part.

Filter on the other hand removes light pollution and associated noise - it lowers noise part of SNR.

You can achieve same result with unmodded camera as you can with modded camera - if you put in more time into particular image. Similarly - you can achieve the same result unfiltered as you would with use of filter - given enough imaging time (if you use it against purely emission target that whose emission lines filter passes - sometimes you won't get the same result if there is something that filter otherwise blocks).

It is just the matter of spending time on target - and we want our results fast, so what ever you can do to improve your time is good thing - that would mean using filter and also if you can - get modded or dedicated astronomy camera (at some point).

[R26 oldtimer]

8 hours ago, Jay6879 said:

 

I've been told a few times already my camera will be useless for nebula so I'm trying to make this work without modifying it!

I wouldn't say that is useless,  but it is really not worth trying with this filter. You should really modify your camera because right now the internal filter blocks almost 75-80% of the Ha emmision.  Remember that this filter will give you a narrowband HOO image, so if you lose all this Ha signal from the ir filter,  in practice all you get is OIII.

If you're after a light pollution filter with an unmodified  camera, then a light pollution filter like the l-pro will suit you best.

[Jay6879]

On 04/06/2021 at 01:02, R26 oldtimer said:

I wouldn't say that is useless,  but it is really not worth trying with this filter. You should really modify your camera because right now the internal filter blocks almost 75-80% of the Ha emmision.  Remember that this filter will give you a narrowband HOO image, so if you lose all this Ha signal from the ir filter,  in practice all you get is OIII.

If you're after a light pollution filter with an unmodified  camera, then a light pollution filter like the l-pro will suit you best.

Welp, that's exactly what I ended up doing. I purchased a modified dslr (selling my old one), and I'm ready to rock. I appreciate all the help here for giving me that little boost to finally just modify and get it over with.

[david_taurus83]

Just bear in mind that you will need to expose for twice as long with that filter.